[Coco] Eureka! I'm Running My Coco 3 with Drivewire 4 Server Finally! or I Found a Bug in HDBDOS v1.4 DW4 Coco 3!

[Aaron Wolfe]

On Tue, Sep 17, 2013 at 7:07 PM, Darren A <mechacoco at gmail.com> wrote:
> On Tue, Sep 17, 2013 at 4:22 PM, Tormod Volden wrote:
>
>> On Tue, Sep 17, 2013 at 11:04 PM, Aaron Wolfe wrote:
>> > IIRC, the sequence is supposed to be sent at 230k, and the server is
>> > supposed to be at 115.
>> > The result of this mismatch is static and detectable, and that is what
>> > the server is looking for.
>>
>> I am curious to know how that works. The HDB-DOS code simply sends an
>> $E6 byte at turbo speed. From what I can see the server simply checks
>> for $E6 as well, but at the slower speed.
>>
>>
> The CoCo sends an $E6 byte (lsb first) at turbo speed.  If the server is
> running at the same speed as the CoCo then it receives $E6 and no change is
> required.  If the server is running at half turbo speed then it will see
> the $E6 byte as $FD.
>
> Darren

Was just about to confirm this :)

Here are the relevant op code values..

public static final byte OP_230K230K = (byte) 230; // 0xE6
public static final byte OP_230K115K = (byte) 253; // 0xFD

OP_230K115K is FD, which is what E6 sent at 230k looks like to a
serial port running at 115k.  I don't know if that holds true for a
115k E6 sent to a 56k serial port... ?

OP_230K230K (E6) is just a NOP so that an E6 on the line when server
is already at 230k doesn't throw a "unknown opcode" error.

I will be publishing an update in the next few minutes to fix the baud
rate change to 2x instead of always 230k.  It is untested but should
work :)

-Aaron